11 research outputs found
Spectroscopic Observations of the WZ Sge-Type Dwarf Nova GW Librae during the 2007 Superoutburst
We carried out an international spectroscopic observation campaign of the
dwarf nova GW Librae (GW Lib) during the 2007 superoutburst. Our observation
period covered the rising phase of the superoutburst, maximum, slowly decaying
phase (plateau), and long fading tail after the rapid decline from the plateau.
The spectral features dramatically changed during the observations. In the
rising phase, only absorption lines of H, H, and H were
present. Around the maximum, the spectrum showed singly-peaked emission lines
of H, He I 5876, He I 6678, He II 4686, and C III/N III as well as
absorption lines of Balmer components and He I. These emission lines
significantly weakened in the latter part of the plateau phase. In the fading
tail, all the Balmer lines and He I 6678 were in emission, as observed in
quiescence. We find that the center of the H emission component was
mostly stable over the whole orbital phase, being consistent with the low
inclination of the system. Comparing with the observational results of WZ Sge
during the 2001 superoutburst, the same type of stars as GW Lib seen with a
high inclination angle, we interpret that the change of the H profile
before the fading tail phase is attributed to a photoionized region formed at
the outer edge of the accretion disk, irradiated from the white dwarf and inner
disk.Comment: 10 pages, 9 figures, accepted for publication in PAS
The ASTRO-H X-ray Observatory
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly
successful X-ray missions initiated by the Institute of Space and Astronautical
Science (ISAS). ASTRO-H will investigate the physics of the high-energy
universe via a suite of four instruments, covering a very wide energy range,
from 0.3 keV to 600 keV. These instruments include a high-resolution,
high-throughput spectrometer sensitive over 0.3-2 keV with high spectral
resolution of Delta E < 7 eV, enabled by a micro-calorimeter array located in
the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers
covering 5-80 keV, located in the focal plane of multilayer-coated, focusing
hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12
keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and
a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the
40-600 keV band. The simultaneous broad bandpass, coupled with high spectral
resolution, will enable the pursuit of a wide variety of important science
themes.Comment: 22 pages, 17 figures, Proceedings of the SPIE Astronomical
Instrumentation "Space Telescopes and Instrumentation 2012: Ultraviolet to
Gamma Ray